1. Field of the Invention
The invention relates to a travelling device, which can be preferably mounted on a vehicle, provided for completely removing and reducing the size of trees, which are growing in a row.
2. The Prior Art
Trees within the scope of the present invention are to be understood as all trees and bushes together with their roots and branches whose roots branch in the ground or are anchored by a only relatively small amount. Thus, preferably low-growing strains having a height of about three to four meters are involved.
Trees which are growing in a row especially include fruit trees on fruit plantations. It is known that after a certain time fruit trees planted in a row on fruit plantations need to be removed and replaced by new young fruit trees since the harvested fruit no longer satisfies the requirements imposed, for example, on colour, shape, taste or keeping quality. Thus, apple trees are renewed about every ten years since the harvested apples from older trees no longer exhibit a red colour typical of the species but in the meantime exhibit a yellow colour.
For replanting it is known that the old trees are sawn off by hand, using a chain saw or the like, just above the ground and laid down, also by hand, next to the tree stumps, the so-called stubs, which initially remain in the ground. The sawn-off trees are then fed to a chipper, again by hand, which reduces the size of the sawn-off trees into small wood chips. Such chippers have been used in practice for decades and are constructed as attachment, superstructure or trailer systems in various sizes and designs. Depending on the type of tools, the chippers are designated as disk, drum or screw chippers. The stubs of the old trees left in the ground are removed in a separate working process using a special stub milling cutter.
A disadvantage with this method of removing the old trees is that a plurality of separate work steps must be carried out, predominantly by hand, to remove the old trees together with the stubs. This time-consuming, physically difficult and dangerous work is usually carried out by several workers and is correspondingly cost-intensive.
It is also known to first press around the old trees growing in a row in some way and then run over them with a mulching device which reduces the size of the old trees together with their stubs during running over and presses the wood chips thereby formed into the ground. The old trees are thus not removed.
For this purpose the mulching device usually comprises a milling cutter which destroys the tree together with stubs and presses the wood chips formed into the ground where they rot.
Pressing in the wood chips takes place over a width of around 20 cm. However, in known mulching devices the milling axis itself is about 2.5 metres wide so that the entire ground is milled and softened over this width. This has the disadvantage that the milled ground absorbs rain water especially easily and thereby becomes difficult to negotiate and difficult to plant.
Such a method also has the disadvantage that the rotting of the wood chips pressed into the ground results in overacidification of the ground which has a negative influence on the health of the newly planted trees.
It has also been found to be negative that the ground is compacted by working in and pressing in the wood chips. As a result, the ground cannot be replanted immediately but must rest for a certain time during which the wood chips pressed into the ground can at least partly rot.
Since the trees are not completely removed but are only worked into the ground, in the case of possibly diseased trees, the diseased wood is also retained in the ground and may be a source of infection for the newly planted trees. Known for example is the so-called fire blight, a bacterial disease which affects fruit trees. This disease is a serious threat for fruit growing. By working wood chips from fruit trees affected by this disease into the ground, the disease-triggering bacteria are not eliminated but can attack the newly planted trees.
In addition, various devices for felling trees and reducing the size of their branches and tops are known predominantly in forestry for facilitating the work and saving costs but these are not suitable for completely removing and reducing the size of trees growing in a row such as fruit trees or bushes.
A process and a drivable machine for felling and processing trees is first known from DE 44 16 195 A1. In this process, the tree which is to be felled is sawn off, debranched, topped and cut into logs by an operating head (harvester) which is borne by a crane. At least during topping, the tree is tilted into the horizontal position by means of an operating head, and the latter is retained such that the top of the tree is pushed into the inlet of a comminution device with the result that at least the top of the tree passes into the comminution device and is coarsely comminuted therein. The vehicle used here bears a pivotably mounted crane with an operating head, and also bears a comminution device with inlet and, optionally, bears a container which is arranged on the vehicle or is suspended thereon and into which the comminuted material is transported, from the comminution device by means of a conveyor.
With this vehicle the working processes such as felling, debranching and cutting of trees and utilisation of the waste wood thereby accumulating, which had hitherto been carried out separately, are combined. The comminuted material is collected in a container and supplied for further utilisation, for example, for combustion in heat and power plants. Advantageously here the branches and tops of the felled trees, which had hitherto been left in the forest, are used as a source of energy. Advantageously in addition, any overacidification of the forest soil by excessive quantities of rotting waste wood from trees is thereby prevented. Material, time and workers can be saved by carrying out the process steps using a single drivable machine.
Furthermore, an apparatus for picking up wood lying in swathes is known from DE 299 17 330 U1. This comprises a combination of a slicing tool with a pick-up device, consisting of a plurality of pick-up and feed rollers arranged transverse to the direction of travel, which can be attached to a forage harvester as a pre-assembly unit.
In this context, a broad deposit of felled wood lying next to the remaining stumps is designated as a swathe.
A continuous work sequence can be achieved with this apparatus by simply running over the swathe. In this case, the swathe is picked up from the ground by means of a first pick-up roller which is constructed with pick-up arbors and is guided to a slicing apparatus by means of a plurality of transport-assisting feed rollers arranged in a row after the first pick-up roller. The feed rollers are provided with transport-assisting elevations (cams) in the form of axially parallel edges. The wood chips of the comminuted swathe are brought back onto the surface by means of a deflecting device or are conveyed into a trailer which runs alongside or is towed, so that the wood chips are supplied to another economic usage, either as fuel or as fertiliser.
Finally a chopper for stalked plants and bushes which cuts down and comminutes trunks standing in a row is known from DE 42 09 947 A1. Such devices are usually attached to a tractor or the like and consist of a cutting unit, conveying elements for the trees and thinner stalked plants and bushes which have been cut down, a comminuting device and an ejecting unit for the comminuted material.
The chopper comprises a vertical rotor with a saw disk for cutting the trunks close to the ground and a vertically rotating screw conveyor located thereabove which seizes the incoming stalked plants and bushes and feeds them almost in perpendicular flow to the cutting disks which are arranged between the sawing disk and the screw conveyor. The comminuted material is ejected laterally into a conveyor pipe.
However, all the methods and apparatus described previously have not proved suitable in practice for completely removing and reducing the size of trees growing in a row in an economical fashion. In all cases, expensive subsequent removal of the tree stump remaining in the ground is required.